A secondary battery having good application to various product groups and good electric characteristics such as high energy density is widely applied to not only portable devices but also an electric vehicle (EV) or a hybrid electric vehicle (HEV) driven by an electric driving source. The secondary battery has a primary advantage of greatly reducing the use of fossil fuels and a secondary advantage of generating no byproduct in use of energy, and thus attracts attention as a new energy source for enhancing environment-friendly and energy-efficient properties.
Lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries or the like are widely used as secondary batteries at the present. Such a unit secondary battery cell has an operating voltage of about 2.5V to 4.2V. Therefore, if a higher output voltage is demanded, a plurality of secondary battery cells may be connected in series to configure a battery pack. In addition, according to a charge/discharge capacity demanded to the battery pack, a plurality of secondary battery cells may also be connected in parallel to configure a battery pack. Therefore, the number of secondary battery cells included in the battery pack may be various set depending on a demanded output voltage or charge/discharge capacity.
Meanwhile, if a plurality of secondary battery cells is connected in series or in parallel to configure a battery pack, in general cases, two or more secondary battery cells are assembled to configure a battery module, a plurality of battery modules is assembled to configure a battery module array, and other components are added to the battery module array, thereby configuring a battery pack. At this time, the shape of the battery module array is determined depending on electric connection or mechanical connection among the plurality of battery modules.
Meanwhile, Korean Unexamined Patent Publication No. 10-2012-0047800 is one of documents disclosing a battery module array and a battery module. In this document, the battery module array is simply expressed as having a box shape, but the entire shape of the battery pack is greatly influenced by the shape of the battery module array. In addition, the shape of the battery module array is greatly influenced by the shape of the battery module. Therefore, there is needed a battery module with good space utilization.